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[Display omitted] • Young, red-fleshed apples (RFA) are rich in bioactive polyphenolic compounds. • Natural deep eutectic solvents (NDES) efficiently extract polyphenolic compounds. • Optimised NDES conditions enhance the yield of phenolics from young RFA. • Phenolic content and bioactivities of NDES and methanol extracts are similar. Red-fleshed apple cultivars with an enhanced content of polyphenolic compounds have attracted increasing interest due to their promising health benefits. Here, we have analysed the polyphenolic content of young, red-fleshed apples (RFA) and optimised extraction conditions of phenolics by utilising natural deep eutectic solvents (NDES). We also compare the antioxidant, neuroprotective and antimicrobial activities of NDES- and methanol-extracted phenolics from young RFA. High-performance liquid chromatography coupled to high-resolution mass spectrometry (HPLC-HRMS) was used for phenolics identification and quantification. Besides young RFA, ripe red-fleshed, young and ripe white-fleshed apples were analysed, revealing that young RFA possess the highest phenolic content (2078.4 ± 4.0 mg gallic acid equivalent/100 g), and that ripe white-fleshed apples contain the least amount of phenolics (545.0 ± 32.0 mg gallic acid equivalent/100 g). The NDES choline chloride-glycerol containing 40 % w/w H 2 O gave similar yields at 40 °C as methanol. In addition, the polyphenolics profile, and bioactivities of the NDES extract from young RFA were comparable that of methanol extracts. Altogether, our data show that NDES extracts of young RFA are a promising source of bioactive polyphenolics with potential applications in diverse sectors, e.g., for functional food production, smart material engineering and natural therapies. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Red-flesh apples as a novel anthocyanin rich food. • Complete metabolic pathways for phenolics from red-flesh apples. • Phloretin glucuronide as specific apple intake biomarker. • Cyanidin galactoside and peonidin galactoside as red-flesh apple intake biomarkers. Abstract The aim of this study was to investigate comprehensively the metabolic pathways and human bioavailability of anthocyanins and other (poly)phenols in an apple matrix, and to elucidate potential intake biomarkers. After the acute intake of a red-fleshed apple freeze-dried snack, plasma and urine were collected and analyzed by UPLC-MS/MS. A total of 37 phase-II and microbial phenolic metabolites were detected in plasma and urine. Among these, phloretin glucuronide, cyanidin-3- O -galactoside (plasma and urine) and peonidin-3- O -galactoside (urine) were the only metabolites detected in all the volunteers and not detected at basal conditions. The maximum urine excretion was detected at 2–4 h, and the main increase in plasma of phloretin glucuronide and cyanidin-3- O -galactoside was observed at 2 h post-intake (61.0 ± 6.82 and 10.3 ± 1.50 nM, respectively). These metabolites could be selected as the best intake biomarkers of red-fleshed apple and might be useful in human intervention studies when studying its health effects. [ABSTRACT FROM AUTHOR]

This study presents a new rapid and non-destructive technique for detecting the degree of red coloration in the flesh of a red-fleshed apple cultivar ‘Kurenai no Yume’. Using a UV–vis-NIR interactance device, interactance data ranging from 190 to 1800 nm was collected non-destructively from the surface of 180 apple fruits. Levels of anthocyanins in the flesh of each sample were determined with a spectrophotometer. Partial least squares (PLS) regression, multiple linear regression (MLR) and artificial neural networks (ANN) modeling analysis were performed to develop models for estimating anthocyanin content from interactance data. Results showed that all the developed models achieved reasonable predictive accuracy. Particularly, the ANN model based on 11 key wavelengths, which achieved consistent performance in predictions with calibration ( R 2 = 0.5798) and test ( R 2 = 0.5324) datasets, were the most promising from the perspective of practical applications. This study strongly suggests that the interactance technique combined with the developed models might provide a new rapid and non-destructive approach for assessing the quality of red-fleshed apples. [ABSTRACT FROM AUTHOR]

• Red-fleshed apple is a rich source of polyphenols and biofortified in anthocyanins. • A complete elucidation of the phenolic metabolism of red-fleshed apple is presented. • Acute and sustained interventions were combined to evaluate phenolic bioavailability. • We report a strong influence of the food matrix on anthocyanins bioavailability. • A selection of the most discriminatory phenolic intake biomarkers was performed. The present study aimed to evaluate the metabolism and bioavailability of anthocyanins (ACN) and other phenolics from red-fleshed apple (RFA) and to define the intake biomarkers compared to common white-fleshed apple (WFA). Acute and sustained (6-week) interventions were combined in a randomized, controlled and parallel study with 121 hypercholesterolemic subjects. Another arm consuming ACN-rich infusion from aronia fruit (ARO) provided matched content and profile of ACN. Plasma, urine and faeces samples were analyzed using UPLC-MS/MS. Results showed higher bioavailability of ACN after ARO compared to RFA, showing a clear apple matrix effect. The dihydrochalcone phloretin-2′- O -glucuronide was the most discriminant intake biomarker of both apples. The urinary peonidin-3- O -galactoside was a good biomarker after both ARO and RFA intakes, whereas peonidin- O -arabinoside was reported to be specific from ARO. The elucidation of the phenolic metabolism and the selection of intake biomarkers is a promising approach to relate phenolic compounds and human health. [ABSTRACT FROM AUTHOR]

• Total aroma OAVs was lowest in expansion period and highest in ripen period. • The concentration of bound form aromas was higher than that of free form. • Esters, aldehydes and terpenes were the main bound form aromas in 'redlove 1'. • 'Fruity' and 'green' were the main odor notes of 'redlove 1' apples. Red-fleshed apple is attracting more and more attentions from both consumers and researchers thanks to its pleasant appearance and flavor. Accumulation and development of aromas of apple fruit are important factors to understand the fruit quality of a new cultivated variety. However, knowledge on the key aroma components development and accumulation of red-fleshed apple (Malus sieversii f. neidzwetzkyana (Dieck) Langenf) in Xinjiang through the fruit developmental periods is insufficient. In this paper, free and bound form aromas of a red-fleshed apple since young fruit period through expansion period and conversion period to ripen period were comparatively studied. We classified aroma substances according to the compound category (esters, aldehydes, alcohols, terpenes, and aromatics), and to the odor types. The concentration of bound form aroma compounds were higher than that of free form throughout the 4 periods and showed different evolution trends. Among the 4 periods, the bound aroma was the most in the expansion period; and terpenoids showed the greatest potential to release free form aromas. Total aromas were found the lowest concentration in expansion period and the highest concentration in ripen period. The observations in this study will provide theoretical support for the research of typical aroma formation regularity of red-fleshed apple, and guide for the aroma enhancement regulation. [ABSTRACT FROM AUTHOR]

• WRKY, AP2 and MYB transcription factor with large differences were screened out. • PPO plays a major role during the early browning stage. • Membrane lipids degradated; produce free fatty acids. Enzymatic browning affects the quality of fresh-cut produce. To elucidate the mechanism regulating the browning of red-fleshed apple, we analyzed the transcriptome and metabolome of freshly cut Meihong apple samples collected at 0, 0.5, and 4 h after cutting. The main differentially abundant metabolites during the browning process were phenols, amino acids and fatty acids. Phenols are substrates for enzymatic browning and most of them are negatively correlated with browning. Amino acids and their derivatives are associated with non-enzymatic browning and most of them are positively correlated with browning. A transmission electron microscopy analysis revealed the degradation of the cell membrane of cut fruit samples, which significantly affected the fatty acid content. The differentially expressed genes were mainly related to plant–pathogen interactions. Polyphenol oxidase (PPO) plays a major role during the early browning stage, but PPO gene expression was not higher than WRKY, AP2 and MYB transcription factor. [ABSTRACT FROM AUTHOR]